High pressure fluids, such as liquid natural gas and propane, are becoming increasingly more common for use in powering vehicles and the like. In filling such a vehicle, a filling hose is operatively attached at its proximal end to a bulk supply tank of liquid natural gas ("LNG"), compressed natural gas ("CNG"), compressed hydrogen ("CH"), or propane and is temporarily removably connected at its opposite distal end to the vehicle by means of a fueling nozzle. The fueling nozzle is temporarily connected in sealed relation to a receiving coupling mounted on the vehicle. It is necessary to remove the fueling nozzle from the receiving coupling on the vehicle before the vehicle drives away. However, on occasion, vehicles are mistakenly driven away before the connected fueling nozzle is removed from the receiving coupling on the vehicle. Resultingly, the fueling nozzle on the filling hose may be forcibly ripped from the receiving coupling on the vehicle, thus causing damage to any one of or all of the filling hose, the inserted fueling nozzle, the receiving coupling, or the vehicle. Indeed, it is quite likely that the filling hose may be forcibly pulled from the outlet of the bulk supply tank of LNG, CNG, CH or propane, or may itself rupture, thus allowing the pressurized LNG or propane to escape unchecked from the bulk storage tank. This situation is, of course, quite dangerous, as it is conducive to explosions and personal injury. Moreover, it is harmful to the environment.
It is therefore necessary, often as regulated by law, to have an automatic shut-off device to stem the flow of LNG, CNG, CH or propane, should the filling hose become ruptured or detached as aforesaid. Typically, such automatic shut-off devices take the form of an automatically releasable shut-off coupling operatively integrated into the filling hose, which shut-off coupling is adapted to release upon an axially directed threshold force being applied along the filling hose. Upon said release, such automatically releasable shut-off couplings typically stem the egress of pressurized LNG, CNG, CH or propane from both segments of the hose which remain respectively attached to the vehicle and the bulk supply tank.
While known automatically releasable shut-off couplings for high pressure fluid applications provide an acceptable level of safety, they suffer from a number of disadvantages. They are generally unduly complicated in their number and arrangement of parts, and are therefore unduly expensive to manufacture and difficult to repair and assemble. They are also generally large, and undesirably heavy. Most importantly, the throughpassage that provides for the flow of fluid therethrough is extremely convoluted and restricted, often having a diameter of less than one millimeter. This unduly restricts flow rates and filling times. Moreover, the width of the throughpassage may vary several times along the longitudinal length of the shut-off coupling. Such changes in width not only further restrict flow rates of pressurized liquid through the coupling, but cause undesirable thermal gradients within the automatically releasable shut-off coupling at each point of width change. Such thermal gradients of highly pressurized fluids such as LNG, CNG, CH and propane may cause freezing and sticking of the mechanisms of the shut-off coupling. Also, prior art automatically releasable shut-off couplings are, by their structural design, typically limited to but a single threshold release force value, with the result that extensive re-design of prior art automatically releasable shut-off couplings may be required to change the threshold release force values for different applications.
It is, therefore, an object of the present invention to provide an automatically releasable shut-off coupling that solves these and other problems associated with known automatically releasable shut-off couplings suitable for high pressure fluid applications.
Accordingly, it is an object of the present invention to provide an automatically releasable shut-off coupling that has relatively fewer interacting parts and is relatively uncomplicated, and therefore inexpensive to manufacture, and relatively easy to assemble and repair.
It is another object of the present invention to provide an automatically releasable shut-off coupling that is smaller and lighter than prior art automatically releasable shut-off couplings.
It is yet another object of the present invention to provide an automatically releasable shut-off coupling having a substantially straight throughpassage for flow of the pressurized fluid through the coupling.
It is a further object of the present invention to provide an automatically releasable shut-off coupling having a straight throughpassage of substantially constant diameter or width along its length.
It is a further object of the present invention to provide an automatically releasable shut-off coupling having a straight throughpassage that does not cause undesirable thermal gradients along its length during the passage therethrough of fluids under high pressures.
It is yet a further object of the present invention to provide an automatically releasable shut-off coupling that is operable at a plurality of threshold release force values without extensive re-design of the coupling or a plurality of its components, but with the one change of a commonly available part.